package Q2;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = scanner.nextInt();

        System.out.println(fun(n));
    }

    public static int fun(int n) {
        if (n == 0 || n == 1) {
            return 1;
        }

        return fun(n - 1) + fun(n - 2);
    }
}
